Can a TMT be positive even after bypass surgery?

Q:I am 50 years old and have hypertension for the past 3 years. Otherwise I am a healthy person. I underwent a medical check up 2 years back and the TMT was found to be positive for induced ischaemia. I was asked to undergo angiography. In the angiography it was found that I had seven blocks. I then underwent a coronary artery bypass grafting (CABG) a year back. Physically, I am as fit as I was before the CABG. I don’t have any health problems since a year. I underwent a medical check up some months back. I went for TMT again. I could complete the test without any difficulty but to my surprise the test came out to be strongly positive for ischaemia. The doctor who tested me told me that there were chances that the surgery would have failed. When I consulted another doctor who did the CABG said that if I didn’t have any problem, then I was fine. He said the TMT was positive in the 4th stage and I need not worry. Now my question is that is it necessary that a TMT has to be normal after a CABG? Can the person be healthy and lead a normal life inspite of having a positive TMT? What other tests should I undergo to know the state of my health after?

A:1. TMT may be abnormal in up to 20-30% of patients after a bypass surgery. Positivity may come due to blockage of the grafts or some times even when the grafts are open, small vessel involvement may give a positive TMT.
2. Certainly a person can lead a normal life even with positive TMT, as long as it is not producing symptoms on ordinary exertion.
3. There are a number of tests, like Stress Dobutamine Echo, Stress Thallium Imaging, PET Imaging, CT angio etc., which may give you some idea, whether your grafts are blocked or not. But these are not definitive tests and they do have false positive and false negative results. The only test, which is full proof is coronary angiography. You must remember that almost 5-10% of grafts get blocked within first one year after bypass surgery and therefore if a person has either recurrence of symptoms or as you have written, a strongly positive TMT, then one must undergo coronary angiography to have a look at the grafts and where exactly are the blockages located. However, if the TMT is positive in the fourth stage only and you have no symptoms and carrying on all activities, then you may decide to pursue aggressive medical management and risk factor control and not probe things any further. However, if you want a full proof answer, then certainly a coronary angiography is mandated.
I think this is about the best we can give you by way of answers, but if you want any more information, I suggest you should consult your treating cardiologist, who would be a better person to answer them.